std::is_swappable_with,std::is_swappable,std::is_nothrow_swappable_with,std::is_nothrow_swappable (3) - Linux Man Pages

std::is_swappable_with,std::is_swappable,std::is_nothrow_swappable_with,std::is_nothrow_swappable: std::is_swappable_with,std::is_swappable,std::is_nothrow_swappable_with,std::is_nothrow_swappable

NAME

std::is_swappable_with,std::is_swappable,std::is_nothrow_swappable_with,std::is_nothrow_swappable - std::is_swappable_with,std::is_swappable,std::is_nothrow_swappable_with,std::is_nothrow_swappable

Synopsis


Defined in header <type_traits>
template< class T, class U > (1) (since C++17)
struct is_swappable_with;
template< class T > (2) (since C++17)
struct is_swappable;
template< class T, class U > (3) (since C++17)
struct is_nothrow_swappable_with;
template< class T > (4) (since C++17)
struct is_nothrow_swappable;


1) If the expressions swap(std::declval<T>(), std::declval<U>()) and swap(std::declval<U>(), std::declval<T>()) are both well-formed in unevaluated context after using std::swap; (see Swappable), provides the member constant value equal true. Otherwise, value is false. Access_checks are performed as if from a context unrelated to either type.
2) If T is not a referenceable type (i.e., possibly cv-qualified void or a function type with a cv-qualifier-seq or a ref-qualifier), provides a member constant value equal to false. Otherwise, provides a member constant value equal to std::is_swappable_with<T&, T&>::value
3) Same as (1), but evaluations of both expressions from (1) are known not to throw exceptions
4) Same as (2), but uses is_nothrow_swappable_with.
T and U shall each be a complete type, (possibly cv-qualified) void, or an array of unknown bound. Otherwise, the behavior is undefined.
If an instantiation of a template above depends, directly or indirectly, on an incomplete type, and that instantiation could yield a different result if that type were hypothetically completed, the behavior is undefined.


Helper variable templates


template <class T, class U> (since C++17)
inline constexpr bool is_swappable_with_v = is_swappable_with<T, U>::value;
template <class T> (since C++17)
inline constexpr bool is_swappable_v = is_swappable<T>::value;
template <class T, class U> (since C++17)
inline constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<T, U>::value;
template <class T> (since C++17)
inline constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<T>::value;


Inherited from std::integral_constant

Member constants


value true if T is swappable with U , false otherwise
         (public static member constant)
[static]

Member functions


              converts the object to bool, returns value
operator bool (public member function)


operator() returns value
              (public member function)
(C++14)

Member types


Type Definition
value_type bool
type std::integral_constant<bool, value>

Notes


This trait does not check anything outside the immediate context of the swap expressions: if the use of T or U would trigger template specializations, generation of implicitly-defined special member functions etc, and those have errors, the actual swap may not compile even if std::is_swappable_with<T,U>::value compiles and evaluates to true.

Example


 This section is incomplete
 Reason: no example

See also


                             swaps the values of two objects
swap (function template)


is_move_assignable
is_trivially_move_assignable
is_nothrow_move_assignable checks if a type has a move assignment operator
                             (class template)
(C++11)
(C++11)
(C++11)